Welcome to the Piano World Piano ForumsOver 2 million posts about pianos, digital pianos, and all types of keyboard instruments
Join the World's Largest Community of Piano Lovers
(it's free)
It's Fun to Play the Piano ... Please Pass It On!

pianoloverus
Yikes! 10000 Post Club Member
Registered: 05/29/01
Posts: 19946
Loc: New York City

I knew that the Mason BB has a full perimeter plate and I just learned that the model A has switched(when I'm not sure) to one also. I am guessing that the soon to unveiled AA will have one too. What are the advantages/disadvantages of a full perimeter plate? Are there other makes that have full perimeter plates?

My understanding is the more mass in the plate, the more inert it will be, and the less it will be involved with the sound. Supposedly, this will help the energy to stay in the soundboard, improving the sustain. I think it is a similar idea to using a 300 lb piece of granite as a speaker stand. The only disadvantage I can think of, is the dirty looks you get from piano movers when you tell them the piano to be moved is a Mason & Hamlin.The AA does have a full perimeter plate. I am sure some here will say it is overkill, or unnecesary.

Most tier one pianos do not have a full perimeter plate.Sure, the full-perimiter plates have lots of sound holes in them, but is less sound getting out of the top of the piano because all that iron is in the way?

Actually *I* don't need any more sound to get out of the top of my BB into my living room, but what about in a concert venue. . . ???

Originally posted by BDB: I've seen a CC with a full perimeter plate, made near the end of production...[/b]

I have also. Best I can recall, it had a section along the straight side with four large port holes like are seen on the curved side of the CC shown in the link. That website reports the tail of the CC as over 40 inches. By my calculations, it's right at 48 at the back of the tail before the last curves to the back, inner measure and right at 50 outer. Massive.

Full perimeter plates are usually heavier. Merits are debatable, and are probably low on the scale of things. I prefer the Bösendorfer with the full perimeter plate, but I couldn't ascribe the difference in the two pianos to that.

Originally posted by pianoloverus: I knew that the Mason BB has a full perimeter plate and I just learned that the model A has switched(when I'm not sure) to one also. I am guessing that the soon to unveiled AA will have one too. What are the advantages/disadvantages of a full perimeter plate? Are there other makes that have full perimeter plates? [/b]

The full parameter plate became moderately popular a century or so back. The pianos that continue to use them were pretty much all designed back in the late 1800s or very early 1900s. (The exceptions, of course, are pianos like the new M&H AA. But then, it is designed to look and feel like it had been designed back in the late 1800s or very early 1900s, deliberately recreating a bygone era.)

The benefits to this design are mostly theoretical: the more massive plate casting is supposed to draw less vibrating energy from the strings and it is supposed to stiffen the rim assembly. The first claim is dubious at best. Compared to other metals, gray iron has excellent vibration damping characteristics. That is, it readily absorbs and dissipates (as heat) vibrating energy. I don’t see how adding more iron well away from the active, structural area of the plate is going to alter this. The second represents overkill in the extreme. The well-made grand rim, especially a rim such as that used in the M&H, is already a stiff and massive structure. It is relatively easy to build an acoustically rigid rim assembly. Simply make it out of a suitably dense and stiff material and brace it adequately. Adding a few bolts to couple a full-parameter plate to the rim is not going to appreciably alter its acoustical characteristics. I know of no tests that show any acoustical benefit for the full-parameter plate design.

Having said all this, the only drawbacks to the design that I am aware of are their cost — obviously, more iron is used and they are a bit more difficult to cast and fit to the rim — and their weight. Pianos are difficult enough to move as it is.

This is my first posting to PW and it couldn't have come at a better time. With regards to the tonal and/or any other effects of a full perimeter plate, I recently purchased a Mason & Hamlin "CC-1", and have started restoring the piano.

The piano is 9'4" but has a second, triangle-shaped, iron plate starting just behind the bass dampers. As other members have posted, I also believe the plate should act as a damper between the hitch pins and the soundboard, however, the purpose for this second plate is the opposite. Apparently, the designers at Mason & Hamlin used this second plate to change the piano's overall tone and volume characteristics.

The second plate is still made of the same metal and the piano was built with a tension-resonator.

This is the first piano I had ever seen with two plates and when I saw the original question posted regarding Mason & Hamlins' full perimeter plates, I wondered if anyone knew more about this model of piano?

I've been giving more thought to the idea of heavy plates also, and their implications to overall energy loss. The earlier BĂ¶sendorfer 6'2" was a piano that also had a full perimeter plate after the style of the Masons.

Thanks for the link to the early CC Chickgrand. The current CC is a significantly better layout than the old model. That earlier CC rim looks like it would make a perfect rim shape for a new Boston concert grand, its got all the hallmarks of the Boston wide bodied back end, and you'd need a packed lunch to take the trip from the rim to the high end of the bass bridge. I'll bet that crossover was a shocker, as a consequence of the widely differing distance of the crossover bridge-ends from the rim. When I visited Mason and Hamlin after Rochester I saw the new AA. These pianos stylistically might look like their earlier pianos but they also have incorporated some very good contemporary thinking. Gone is the hockey stick treble bridge and the cross over is moved up to D30 from memory. The nice new log style treble scale is a welcome addition to the instrument. This piano is a big scaling improvement over the opposition in that size of instrument - Walter accepted.

During the mid 70's, there was a full-perimeter-plate 6'2" BĂ¶se in a Sydney studio called United Sound (before they built the Sydney Entertainment Centre, which was preceded by the demolition of the United Sound building). It was quite a nice instrument in spite of its B27 break. For those of you who might remember the Dudley Moore Trio LP, Song for Suzy, that LP was recorded on the above mentioned 6'2" in Sydney. The LP was quite a good recording with the exception of an annoying flutter which persisted throughout the entire album. Clearly one of their tape machines, for the production process, wasn't exactly in good shape.

Back to plate weights. Ever since I rebuilt an SD-10 Baldwin back in 1988, the plate issue has been hovering around in my head as a possible factor which might aid sustain in a piano.

Something I've been doing, as an anecdotal experiment in recent times, is to place a hand lightly on the plate while striking a thick chord with the other hand. I've found that pianos such as Yamaha, Steinway and the RX Kawai, with their very lightly built plates, tend to be noticeably more active in the plate than heavier plated pianos such as the SD-10 and our own 225 piano. BĂ¶sendorfers also have a slightly heavier plate which tends to be a little more inert. Now while I understand what Del is saying about the hi-hysteresis characteristics of grey iron, I can't help thinking that, despite the lossy nature of the metal, a higher mass, higher web thickness plate should lose less energy if it is vibrating a lot less than a relative light flimsy plate. Another piano which would seem to lend support to this idea is the Welmar or Marshall and Rose grand (both made out of the UK Whelpdale Maxwell and Codd factory - now closed). These pianos had quite massive plates and a relatively light rims like a BĂ¶sendorfer, yet they were known for their good sustaining qualities. The Welmar plate-belt between the bass and treble bridges was around 1" thick.

Anyhow, its just one more idea thrown into the mix. The jury may be still out on this one but for me, the heavier plate giving better sustain is gaining cred' as I get older.

I realise that soundboard design, ie. mass/stiffness and radiating area will also influence sustain and impedance, but the plates do seem to be contributing to the overall result as well.

I saw an old (~1900) Boesendorfer with a full perimeter plate. A smaller piano, under 2 meters. The reason for the full perimeter plate seemd to be that it lacked any beams underneath. So probably they thought that the plate could stiffen the rim in the absence of beam support.